docs: def sendError(self, errorcode):
          """This method uses the socket passed, and uses the errorcode to
          compose and send an error packet."""
          log.debug("In sendError, being asked to send error %d", errorcode)
          errpkt = TftpPacketERR()
          errpkt.errorcode = errorcode
          if self.context.tidport == None:
              log.debug("Error packet received outside session. Discarding")
          else:
              self.context.sock.sendto(errpkt.encode().buffer,
                                       (self.context.host,
                                        self.context.tidport))
          self.context.last_pkt = errpkt